01/02/2016 4:41 PM AEDT | Updated 15/07/2016 12:51 PM AEST

Police Warn Young Aussies About Bad Batch Of Synthetic Cannabis After Dean Shield's Tragic Death

Nigel Killeen via Getty Images
Victorian Police barrier/crime scene tapeMelbourne, Australia

Police have warned that Australians do not know what they are consuming when they take synthetic cannabis, after a 17-year-old boy in New South Wales was found dead in a drain on Saturday night.

With two more youths in the area falling critically ill on Sunday morning, detectives have launched a major investigation into a bad batch of synthetic cannabis in the Hunter Valley region.

Central Hunter crime manager Detective Inspector Mitch Dubojski held a press conference held on Monday afternoon warning Australians about the risk of drug-taking, calling Shield's death the most tragic of circumstances.

“You just simply don’t know what you’re getting when you buy and use these substances,” said Detective Dubojski.

Detective Dubojski said Dean Shield’s family were grief-stricken over the tragedy and urged the public to call emergency services immediately if they notice someone having a strange reaction to a suspected drug.

"Anyone using any form of drugs is putting themselves at extreme peril," said Detective Dubojski.

“You’re taking your life in your hands by using it, quite literally.”

Dean Shield is suspected to have purchased a form of synthetic cannabis hours before the 17-year-old's body was found early on Saturday night by Rutherford resident Dave Pettit, who was mowing the lawn in a laneway near his home.

"My mower hit the edge of a drain in the laneway - then I saw an arm sticking out," Mr Pettit told Fairfax.

"I shook him and tried to wake him up.

"He didn't move and I had a pretty good idea he was dead.

"Then I just rang triple zero and waited for police."

Dave Petit was moving the lawn near his Rutherford home when he found Dean Shield's body.

Synthetic cannabis was banned in NSW in 2013 -- following a number deaths including in the Hunter Valley region -- but authorities suspect manufacturers are changing the chemical compounds to get around the laws, or selling on the black market instead.

Autopsy results expected to come through in a few days will confirm the cause of Shield’s death although toxicology results are expected to take longer, said Detective Dubojski.

Police have confirmed the two youths, both 22, who fell ill on Sunday are not in life-threatening conditions.